Carbon steel, non-alloy steel, black steel...

17.8.2023

All these terms describe a material that contains a very small percentage of alloying elements and therefore cannot be considered stainless.

During production and storage, products made from structural steels (excluding corrosion-resistant ones) develop layers of iron oxide on the surface.

During the manufacturing and processing of steel products, scale forms due to the influence of heat. When exposed to moisture, this becomes rust.

The resulting layer of corrosion products is undesirable in most technical applications. The removal and subsequent treatment of the cleaned steel surface are the focus of FK System – Surface Treatments, Ltd.

Different steel surfaces are shown in the combined photograph.

The first image displays the initial surface of a pipe with layers of scale and rust.
The second image depicts the same pipe after cleaning through a chemical process – pickling followed by passivation of the surface. Cleaning is carried out by immersing the respective part into a liquid bath. The cleaned and passivated surface is recommended to be conserved with another substance to extend the duration of its corrosion resistance. This method of cleaning and surface protection is suitable where applying a protective coating is not feasible. An example of this is the interior surfaces of pipes and pipeline components.
The third image illustrates a surface cleaned by abrasive blasting using steel grit. Blasted surfaces are best suited as a pre-treatment for applying protective coatings. Blasting can clean any accessible surface, as long as the formation of a specific relief on the blasted part's surface is not detrimental. The limitation comes with thin sheets (up to 2mm), where deformation may occur.
The fourth image shows the applied base coat on the blasted surface of the pipe.